Having 4G LTE connectivity on a mobile device is great and all, but when its signal begins to weaken, iOS takes it upon itself to switch to 3G. This is perfectly reasonable, of course, since it conserves battery and makes practical sense to run only 3G where LTE coverage is not necessarily firing to its maximum capacity, but if you don't want to be mollycoddled by Apple in this regard, then there's no actual way to halt the auto-switch to 3G. As with so many limitations within the iOS software, though, there's a remedial tweak out to resolve the issue, and a new entry over at the BigBoss repository will lock your cellular data signal to 4G LTE even when it begins to fade out.